Online advertising is largely dominated by advertisements placed on Web pages. Typically, advertisers provide an ad network with target keywords for an ad campaign, and the ad network selects an advertisement to place on a host Web page by determining which ad campaigns have keywords that best match the content of the Web page.
Additionally, some computer-implemented online games rely on advertising to generate at least a portion of the game's revenue. Unfortunately, these online games typically adopt ad bidding systems that have been optimized for advertising on Web pages, and thus do not take advantage of special features that are made available by online games.